Party-line telephone system.



W. W. DEAN.

PARTY LINE TELEPHONE SYSTEM. APPLICATION FILED JAN. 22. 1904.

PATENTED FEB. 11, 1908.

tillldi 'l lld Pr-lt'li r OFI CE}.

WILLIAM W. DEAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO KE'IiLOGG *SWITCEIBOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, Jr CORPORATION -OF ILLINOIS.

PARTY-LINE 'IELEPHUNE SYSTEM.

No. iii/$ 2 79.

Specification of Letters Patent.

Patented Feb. .11, 1908.

Application filed January 22, 1904. Serial No. 190.175.

' such lines.

My invention particularly relates to systeam having the central office a plurality of generators adapted to impress upon the line rei erably alternating current of differ ent 'requencies, and consists in providing a separate eleetro-magnetic device at each substatlon, which is furnished wlth a tuned reed having a certain definite rate of vibratime, and this device is'arranged to suitably control the signaling bell at the substation. In my preierred arrangement, I locate the said harmonlcdevice and an ordlnary polarized signalingbell in a bridge of the line normally connected therewith at" the central ofiice, I preferably include in'each of the bridges of the signaling devices a suitable condenser which serves to prevent the flow of steady current but permits the passage of the ringing current.

My invention is illustrated in the accompanying drawing in which the same reference characters are used throughout and inwhich Figure 1 is a diagram of, a telephone system embodying my improvements; Fig. 2 is a side eievation of theharmonic device that I "prefer to use, and Fig. 3 is adiagrame matic view ofthe substation circuits that are preferably em'pioyed. a is a modifica tion of my invention by means of'which the capacity and impedance the circuit current flow through .a particular harmonic.

device is modified by the adjustment of the device.

In Fig. l, L indicates a telephonellinerf' the poly-station type extending in two limbs 2 and 3 from the substations A, B, and D to the central office E, where it is fitted-with the usual appurtenances including a line signal 5, an answering jack and a plurality of multiple jacks (such as J and J in any desired numher. The line conductor 3 is norrrialiy connected with branch conductor i, which isccnnected withth-e common battery 5 leadin from the live ole of the central common battery BF, wine the-line conductor 2 is normally groundedtlu'ough includes the winding of the line relay R which controls through; its normally o contact the local circuit of the line sigma while a cut-off relay R serves to disconnect said line conductors 2 and 3 humtheir-norangle late llsecured to the yoke 12 which joins-t a rear ends of thecoresof coils 9 and 10. The core of the magnet 10 iseextended cf the is legged to ground from the a branch connection 6.. The conductor a beyond the forward end of the coil and the tuned .r'eed rigidly secured thereto. This reed. consists'of a spring strip 13 secured at its lower end to the projecting end of the core of coil 10 and at its upper end to the armature 14 which carries u on its outer face an adjustable weight 15 't at is secured in any longitudinal position thereon by means of a suitable set screw 16 passing throu h a slot inxthe Weight 15 and threadin into t e-armature 14. The upper reduce end'of the armature 1 4 is adapted when the reed is vibrated to strike the adjustable set screw 17 carried in the lower end of a comparativ'ely heavy contact 18 that is loosely insulating plate 21 that is secured by suitable screws to the late 8. Said bracket 20 also servesfthroug 'the medium of binding screw 20 and an intersecting aperture as a binding postor terminalfor the contact 17.

An adjustable screw contact 22 is carried by mounted upon a suitable insulating block 26 secured to plate 8 and serve as te'rminals'for the coils 9 and 10 of the horse-shoe magnet. The forward end of the core of the magnet 91, may be provided with an adjustable pole piece 27 consisting of a threaded portion screwing into the end of the core. When an alternating or pulsating current of the proper frequency traverses the coils 9 and 10 of this device, the armature 14 is suitably actuated and the reed is caused to vibrate. In the vibration of the reed it strikes the screw 17 of the heavy contact 18 and serves to swing said contact 18 out of engagement with the contact 22. Owing to the inertia of the contact 18 the rapid vibration of the tuned reed does not permit the same to close u on the contact 22 so that the circuit control ed between the contacts 18 and 22 is thus continuously opened. The operative rate ofactuation of this device is thus the natural rate of vibration of the reed as modi- "fied by its action in striking against the weighted contact 18, and the frequency of the operating current must closely approximate this resultant rate of actuation in order to successfully operate the device. Likewise the said frequency must be sufliciently close to the natural rate of vibration of the reedto start the same from a state of rest. The rate of vibration of the reed may be varied by adjusting the weight 15 along the armature.

In Fig. 1 I have shown in simple diagram the substation apparatus including the harmonic device. At each station the said device 7 is placed in a bridge of the line conductors 2 and 3 together with a suitable condenser 30 and an ordinary polarized or alternating current signaling bell 3].. The said contacts 18 and 22 of the harmonic device 7 serve to normally short circuit the bell 31 through the medium of branch conductors 32 and 33 connected from opposite sides of the bell 31 to the said contacts. A trans mitter 34, and receiver 35 are adapted to be included. in a bridge of the line conductors when the receiver is removed from the switch hook 36. The same apparatus is shown at each substation but the weight 15 is adjusted to dilierent positions upon the armature 14 and hence the reeds have different rates of actuation; The reed at station A, for example, is preferably adjusted to cause the reed to operate at 1000 vibrations per second; that at station B at 2000 vibratlons per second, and those at stations C and D at 3000 and 4000 vibrations per second respectively.

At thecentIal office, the o impressing ringing current of the desired frequency upon the telephone line. This cord circuit comprises-as usual, an answering a plug P and a calling plug P having tip. and sleeve-contacts adapted to register respectively with the corresponding contacts of the erators cord 'clrcult 1s provided with suita he means for spring jacks of the" telephone line, the tip contacts of said plugs being joined by means.

of flexible strands t andt and the interposed condenser- 0 while their sleeve con-' tacts are similarly united by the strands s and s and the interposed condenser 0 The supervisory relays rand r are adapted to be connected upon opposite sides-of the common battery B in a bridge at the answering end of the'cord circuit, said relays serving to control the local circuit of the supervisory lamp S associated with the answering plug P, while similar su ervisory relays r and 1* I are connected in ii e ,manner with the battery B across the calling end of the cord circuit and similarlycontrol the local circuit of the supervisory signal S The operators head telephone 37, the secondary 'of -herinare adapted to be bridged across the calling end of the cord circuit by means of the springs 39 of any suitable listening key, while her transmitter 40 and the primary of her induction coil are adapted to be charged from any suitable source of current which may be the battery B or B Associated with the calling end of the cord .duction coil 38 and a suitable condenser c with the reeds operating at the rates s'pecifled, the generator 41 is capable of developmg a ringing current preferably alternating in character having a. frequency of 1000 cycles per minute, the generator 42 of 2000 cycles per minute, the generator 43 of 3000 cyclesper minute and the generator 44 of 4000 cycles. The opposite terminals of said generators are shown. grounded, while the sleeve springs of the ringing keys when they.

are actuated connect with the branch conductors 45 and 46 leading to the battery lead 5, a suitable resistance 47 being included in said conductor 46.

straws all The operation of establishing the connection with the calling subscriberiscarried out in the usual manner. The subscriber taking up his receiver closes a circuit over the tele phone line from the battery or B, and operates his line relay R to actuate the signal S.-

Uponobserving the signal the-operator inserts the answering plug P of her cord circuit in the answering jack of. the telephone line and depresses her listening key to connect her telephone with the cord circuit that she has used to answer the subscriber.- The insertion of the plu P causes currentirorn the batter to. flow trough the cut-off relay of the cal ing line to thereby disconnect the line relay R- to render the line signal inoperative. After learning the order of the calling subscriber the wanted line is tested in the usua manner by touching the tip of the calling plug P to the test ring of the multiple jack of the said line.

If the line is found idle the calling plug is inserted and the ringing key correspc cling to the party wanted. upon the line is operated.- For example, having inserted the calling plug P in one of the jacks of the line L the de pression ofthe ringing key a. causes current from the generator 41 to flow from ground over the tip side of the telephone line through the shuntieireuits including the con ductors 33 and .32 and contacts 18 and 22,

and thence through the harmonic devices 7 and the condensers 30 at the substations. Owing to the fact that this ringing'current 1S of the frequency corresponding to the signaling devices 7 at the substation A, only this line to ground.

device is operated, and when so operated it opens the shunt circuit about the signaling bell 3 1 at said station which then permits ringing current to flOW/ directly through the si naling bell 31 and actuates the same to ca ll the subscriber. The depression of any of the other ringing keys will, in a similar man ner, operate the signaling bell'at the corresponding stations on the telephone line and will not operate the. others. 1

After the subscriber has been called but before his response current from the battery B flows through the supervisory relay 1' and through the cut-off relay R of the telephone This supervisory relay closes the local circuit of the si ciated With-the plug P which is ighted until the subscriber responds.

the-metallic circuit of the telephone line is completed and current flows back to the central ofiice through the supervisory relay r which is energized and retires the said supervisory signal.

Dunn g conversation the battery i3 is sendingcurrent out over the telephone line L to.

operate the subscribers transmitter While the battery B is sending current out over the calling subscriberls line for the operation of his transmitter. At the termination of the al S asso- In thus respondingcuits to steady currents andv ermits the relays r and r to close the lone circuits of the corresponding supervisory signals S and 5 which are lighted to indicate to the operator that the conversationhais terminated. The operator may then Withdraw the lugs from the telephone lines and restore al parts. to normal condition.

The substation arrangement shown in Fig. 3 is preferred. This includes, in additionto the parts shown in Fig. I, suitable retaildation coil left-and the con-nectiens are such that normally the bridge of the signaling de vices is closedthreugh the contacts of the hook switch 36, but when the receiver is lifted from. the hook said bridge is opened i circuit. Thusthe condenser 30 is utilized for both talking and signaling.

in the arrangement shown in Fig. .1, no provisionis made for adjusting the capacities of the condensers 30 and the inductance of the harmonic device'- 7- to make their branches resonant to the ringing currents but it is obvious that this may be readily M done.

ill practical manner of approximately so adjusting these parts is to arrange the two coils 9. and 10 of the device 7 in such manner that at some of thestations they-may be; connected in series and at others they may be connected in parallel. Such an arrange Inent is shown in Fig. 4:, in which the station marked A will be called by. the use of a low freguency current and the station marked B will: be called by the use of a high frequency current. v

While I have described one specific man her of utilizing the harmonic devices and, in general, of carrying out the invention, 1' wouldhave it understood that the invention is not to be so limited in all respects as ,vari ous modifications and arrangements maybe made Without departing from the intended sco e of the invention.

. lat I claim and desire to secure by Lctters Patent is: i

1. In a party linetelephone system, the combination with a telephone line, of a plurality of substations located on the line, a harmonic device at each substation adapted to respond to current of predetermined frequencies, a bell also at each substation, a shunt circuit of the bell adapted t be continuously broken during the actuation of' the device, and a sourceof current at the central office for each substation adapted to impress current upon the lineof'the proper frequenfill ' V substantially as described.

rality of substations located on the line, a harmonic device at each substation adapted to respond to current of predetermined frequencies, a signaling bell at each substa tion, a shunt ofv the bell continuously broken by the actuation of-the device, a source of. current at the central office adapted to im-.

press u on the line ringing current of the proper requencies to actuate said harmonic devices, and means whereby'when the said 4 shunt circuits are opened the said bells are operated by the current from the said source independently of intervening means at the central station, substantially as described.

3. In a party line telephone system, the combination with a telephone line, of a plurality ofsubst'ations located on the line, a harmonic device and a bell connected in branches from the line conductors at the.

substations, the said harmonic devices controlling shunts of the said bells, means at the,

central oflice for impressing upon the line current of the roper fre uencies to actuate the harmonic evices, an maintain a break in said shunt, the bells when the shunt circuits are opened being operated by the same current that actuates the harmonic devices,

4. In a party line tele hone system, the combination with atelep one line, of aplurality ofsubstations located on the'line, a

harmonic device and a signaling bell in a. bridge of'the line conductorsat each sub-- station, the said devices each .controlling a shunt circuit of the associated bell, and

' ada ted to maintain a break in said .shunt during the actuation of the device, and means at the central office for impressing upon the line ringing currentof frequencies corresponding to the rates of actuationof said devices,

said bells being also actuated by said cure.

rents when the associated harmonic device opens the shunt, substantially as described.

5. In a party line tele hone system; the combination with a telep one. line, of'a plurality of substations located on the line; a

condenser,- harmonic device and bell located in a bridge of the line conductors at each substation; said devices controlling shunts of the corresponding bells, and being adapted to maintain a break in said shunt during actuation, means at the central voflice for impressing upon-the line current of frequencies corresponding .to t e rates of actuation of said devices, the said bells responding to the same current flow when their shunts are opened by the said devices, substantially as described.

6. In a party line telephone system, the

combination with a telep one line, of a plurality of'substations located on the line, .a

aling device at each substa-- harmonic si tion adapte to respond to current of redetermined' fre uencies; a signaling be a. .shunt of said bel controlled through the normally closed contacts of said harmonic device, a weighted member adapted to .be. operated by the vibrating, reed of said device' when whereby when the reed is actuated said member owing to its momentum opens said contacts, the o erative rate of actuation of the said device eing the natural rate of the reed as modified by the action ofthe said member in being struck, and means for impressing current upon the line of a frequency correspondin to the said operative rate of actuation an sufiiciently close to the natural reed to start the .same, substantially as described.

Signed b me at Chicago, county of Cook, State of 11 ois, this 31st day of December 4 1903. I

WILLIAM W. DEAN.

Witnesses:

E. A. GARLOCK, ROBERT Lnwrs AMEs 

